This study is devoted to the hitherto largely disregarded natural fools, who form part of the broad spectrum of fools in the Middle Ages and Early Modern Age. Using the farcical novel Histories of Claus Fool, which was widely read in the 16th and 17th centuries, it examines the notion of natural foolishness and its use by the Protestant writer Wolfgang Büttner. The study develops the functions performed by natural fools in the cultural context of the age. It explicates why these fools were ridiculed while at the same time being regarded as marvels, examples and soothsayers.